The <commit> does not prevent the parser to backtrack through it - it's different from the Perl6 <commit> or Perl5 (*COMMIT). With Parse::RecDescent, a <commit> only means not to try any other alternative for the current rule. Which means for your job_statement production to not thrown an error if, after matching job_name, it's force to backtrack.

You could make <commit> behave the way it does in Perl6 by adding, for each rule that has a <commit> in one of its alternatives, a final <uncommit><reject> alternative.